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by Wei Perng, PhD


I have always loved dessert. As a researcher in the field of nutrition and obesity prevention, I am embarrassed to say that I love it more than “real food.” My mother believes that my unrelenting sweet tooth stems from her own preference for anything sweet when she was pregnant with me – pastries, donuts, ice cream, pudding, chocolate – you name it. I always thought this was an old wives’ tale until I stumbled upon some interesting literature while working on a book chapter on the effect of maternal diet on the long-term health of the child. Might we develop preferences for food even before we are born?
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Wei Perng at age 2
The answer seems to be yes. A fetus’ taste buds begin to develop at six weeks of gestation. Around 12 weeks, the baby begins gulping down amniotic fluid, the protective liquid surrounding the fetus that is flavored by the food and beverages the mother has eaten. By 28 weeks, the olfactory bulb, a brain structure responsible for smell, develops and the unborn baby has a powerful sense of smell. These developmental milestones make it very likely that what your mom eats during pregnancy could influence your own food preferences later in life based on sheer familiarity.

Animal models provide support for this hypothesis. Todrank and colleagues fed one group of pregnant mice a flavor-supplemented food while the other group received non-flavored standard food. What happened? Pups of mothers who were fed flavored food had larger olfactory bulbs than those whose mothers ate standard food. Furthermore, when the pups were 20 days old, they showed a clear preference for the food they were exposed to prenatally, providing evidence for this notion of “prenatal flavor-programming.”

There are also studies in humans suggesting that a woman’s food choices can shape her baby’s palate. In a small trial, 46 pregnant women followed one of three regimens during pregnancy: (1) drank carrot juice during pregnancy and stopped after the baby was born, (2) drank water during pregnancy and began drinking carrot juice after the baby was born, or (3) avoided carrot juice during and after pregnancy (e.g. drank water only). Regimen #1 enabled the researchers to assess the effect of “carrot-flavored” amniotic fluid, whereas Regimen #2 permitted them to test for an effect of “flavored” breast milk. Around five months postpartum, the infants were videotaped as they were fed cereal with water vs. cereal with carrot juice; this was their first exposure to carrot-flavored food. As predicted, infants  exposed to carrots in utero or during breastfeeding showed a more favorable response to the carrot-flavored cereal.

The concept of prenatal flavor programming can be a potent motivator for pregnant women to eat healthfully. Some healthcare practitioners believe that a woman’s diet during pregnancy could have potential to reduce risk of diabetes and obesity in offspring. While this is an empowering concept, behavior change is challenging and other factors that influence dietary habits, such as cost and availability of fresh foods, are hurdles to healthy eating. And of course, eating lots of veggies during pregnancy will not guarantee that your child will reach for Brussel sprouts over a Twix. As described in a recent post, our inherent preference for sweets evolved because they are high in energy, and our tendency to reject bitter vegetables is likely related to the fact that poisonous compounds are bitter. Nevertheless, exposing infants to these flavors in the womb may make kids more responsive when their parents encourage them to eat veggies later in life!

 


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